<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title>使用canvas画圆</title>
	</head>
	<body>
		<div id="pic">
			<canvas id="circle" width="400px" height="400px"></canvas>
		</div>
		<script type="text/javascript">
			var context=document.getElementById("circle").getContext("2d");
			context.beginPath();
			context.arc(200,150,100,0,Math.PI*2,true);
			context.closePath();
			context.fillStyle="rgba(25,25,25,0.4)";
			context.fill();
		</script>
	</body>
</html>
